Grout applicator

ABSTRACT

An apparatus for applying grout in a region between a tubular sub-sea foundation pile and a leg of an offshore structure inserted into the foundation pile is provided. The apparatus includes a rigid tube adapted to be inserted into the region. The rigid tube includes an inlet for receiving grout, and an outlet. A method for grout application is also provided.

This invention relates generally to a grout applicator. More specifically, although not exclusively, this invention relates to an apparatus for applying grout to the leg of an offshore structure and a method of fixing an offshore structure to a pre-piled foundation pile.

BACKGROUND

Offshore structures, commonly present in both the offshore wind and offshore oil and gas industries, most often include a structural jacket supporting a payload above the surface of the water. In the offshore wind industry, the payload is a wind turbine, and in the offshore oil and gas industry, the payload tends to be a processing and/or accommodation platform.

The structural jacket is secured to the seabed via one or more foundation piles, which often take the form of hollow tubes piled into the seabed. In order to secure the structural jacket to the foundation piles, and therefore the seabed, a cementitious material commonly known as grout is applied to the foundation. The grout is applied such that the interface between each foundation pile and respective leg of the jacket is filled. The grout is subsequently left to cure. Conventionally, the grout is applied from pump unit on the surface via a pipe or hose. In particular and most commonly, suitable piping or hoses are provided within the leg(s) and stab portion of the leg(s) of the jacket structure to provide the grout to the desired region(s).

SUMMARY OF THE INVENTION

According to an aspect of the invention, there is provided an apparatus for applying grout in a region, e.g. an annular region, between a tubular sub-sea foundation pile and a leg of an offshore structure inserted into the foundation pile, the apparatus comprising a rigid tube adapted or configured to be inserted into the region, the rigid tube comprising an inlet for receiving grout, and an outlet.

The leg of the offshore structure may not comprise any internal and/or integrated means for conveying grout into the tubular sub-sea foundation pile.

The outlet may be disposed in a sidewall of the rigid tube.

The rigid tube may comprise a closed end, e.g. opposite to the inlet end.

The outlet may be disposed in the sidewall of the rigid tube proximate to the closed end.

The leg of the offshore structure may be or comprise a jacket leg. The leg of the offshore structure or jacket may be inserted into an open end of the foundation pile. The foundation pile may be a pre-piled foundation pile.

The rigid tube may comprise a plurality of outlets. The plurality of outlets may be disposed in the sidewall of the rigid tube. The outlets may be circumferentially spaced thereabout. The outlets may be equally spaced circumferentially thereabout.

The sidewall of the rigid tube may comprise markings or indicia. The markings or indicia may provide, or be configured to provide, in use, an indication of the depth to which the outlet is inserted into a foundation pile.

The markings or indicia may provide, or be configured to provide, in use, an indication of the depth to which the rigid tube, closed end or outlet is inserted into a foundation pile.

The markings or indicia may be printed, engraved and/or embossed on or into the sidewall of the rigid tube.

The closed end may be provided by a plug or cap. The plug or cap may be removable. The closed end may be provided by an attached, e.g. welded, metal disc.

The rigid tube may be formed of steel, e.g. stainless steel or galvanized steel. In examples, the rigid tube may be formed of any suitable metal alloy. The rigid tube may be formed of a composite, e.g. carbon fibre reinforced polymer (CFRP).

The apparatus may further comprise a flexible conduit or hose. The flexible conduit or hose may have a first end for connection with a source of grout, for example a pump unit. The flexible conduit or hose may have a second end connected to, or for connection with, the rigid tube.

The rigid tube may be removably connected to or connectable with the flexible conduit or hose.

The first end of rigid tube may be connected to, or for connection with, the flexible conduit or hose.

It will be appreciated that the apparatus is separate from the offshore structure and the foundation pile. For example, the apparatus may be carried onboard, and deployed from, a seagoing vessel, e.g. a supply ship.

By providing the apparatus separate from the offshore structure and the foundation pile, it is reusable such that it can be used on multiple offshore structures. Such an apparatus is particularly beneficial when there is no integrated means for conveying grout into the foundation pile, e.g. a conduit integrated into the offshore structure or foundation pile.

The rigid tube may have an internal, or external, diameter of between 2 and 4 inches. The flexible conduit may have an internal, or external, diameter of between 2 and 4 inches.

The apparatus may comprise a flange. The flange may be configured to be attached to the leg. The flange many be configured to limit the extent to which the leg can be inserted into the foundation pile. Advantageously, the flange can be attached to the leg to define a spacing between an end of the leg and the sea floor within the foundation pile.

The apparatus or flange may comprise a funnel guide. The funnel guide may be arranged to guide, e.g. in use, the rigid tube into the foundation pile.

The funnel guide may comprise a conical portion. The conical portion may be configured, in use, to be located on or proximate an open end of a foundation pile. The funnel guide or conical portion may be configured to guide the rigid tube into the foundation pile.

The flange may be a radially-extending flange. The flange may be configured to engage with, or be positioned on, an open end of a foundation pile. The flange may have one or more apertures extending therethrough, e.g. for locating the rigid tube, in use, relative to a foundation pile. The or each aperture may have a conical portion extending therefrom or thereabout, e.g. to guide the rigid tube towards the respective aperture.

The flange may comprise three apertures circumferentially spaced, e.g. equally spaced, thereabout. The apertures may be configured, in use, to position the rigid tube at circumferential positions relative to the foundation pile. The flange may comprise apertures spaced 45, 90, 120 or 180 degrees apart.

According to another aspect of the invention, there is provided an offshore structure foundation building system, comprising an apparatus as described above, an offshore structure having a leg, and a foundation pile.

Preferably, the leg has no integrated means for conveying grout into the foundation pile. In particular, there is preferably no conduit integrated into the offshore structure or foundation pile.

According to another aspect of the invention, there is provided a kit of parts comprising a rigid tube as described above and a flexible conduit or hose as described above.

The kit of parts may comprise a source of grout, for example a pump unit or grout pump. Additionally or alternatively, the source of grout may comprise a hopper or other storage tank for grout.

According to another aspect of the invention, there is provided a method of fixing an offshore structure to a sub-sea foundation pile, wherein the foundation pile comprises a tube piled into the sea floor and the offshore structure comprises a leg inserted into the foundation pile, wherein the method comprises lowering a rigid tube into a region, e.g. an annular region, described between the foundation pile and the leg such than an outlet of the rigid tube is at a first position, and applying grout to a first region between an end of the leg and the sea floor within the foundation pile via the rigid tube.

The foundation pile may be a pre-piled foundation pile. The leg of the offshore structure may not comprise any internal and/or integrated means for conveying grout into the tubular sub-sea foundation pile.

The rigid tube may be inserted into the region, e.g. annular region, such that when in the first position, it rests on the sea floor within the foundation pile. The rigid tube may be inserted into the region such that when in the first position, the closed end is on contact with or rests on the sea floor. The rigid tube may be inserted into the region such that when in the first position, the closed end lies proximate or adjacent the sea floor.

After grout is applied to the first region, the method may comprise raising the rigid tube such that the outlet is at a second position, above the first position. The method may comprise supplying grout to a second region, the second region being an annular region described between the leg and foundation pile.

When the outlet is at the second position, grout may be conveyed until it fills or overflows the foundation pile.

Filling or overflow of grout from the foundation pile may be determined acoustically and/or visually. Filling or overflow of grout from the foundation pile may be determined using a remotely operated vehicle (ROV). Filling or overflow of grout from the foundation pile may be determined using a density gauge or density meter, e.g. an ultrasonic density gauge or meter or nuclear density gauge or meter.

The offshore structure may be configured to support a payload above the surface of water. The payload may be mounted to the offshore structure, e.g. a jacket thereof, after grouting has been completed. The payload may be or may comprise a wind turbine or an oil and gas platform.

The present method may be particularly advantageous in the case that the payload is a wind turbine. In such a case, there may be cyclical side loading applied to the offshore structure, e.g. due to wind and/or operation of the wind turbine. The structural integrity of the foundation, as a result of the present invention, may provide a more reliable structure when subject to such side loading.

Within the scope of this application it is expressly intended that the various aspects, embodiments, examples and alternatives set out in the preceding paragraphs, in the claims and/or in the following description and drawings, and in particular the individual features thereof, may be taken independently or in any combination. That is, all embodiments and/or features of any embodiment can be combined in any way and/or combination, unless such features are incompatible. For the avoidance of doubt, the terms “may”, “and/or”, “e.g.”, “for example” and any similar term as used herein should be interpreted as non-limiting such that any feature so-described need not be present. Indeed, any combination of optional features is expressly envisaged without departing from the scope of the invention, whether or not these are expressly claimed. The applicant reserves the right to change any originally filed claim or file any new claim accordingly, including the right to amend any originally filed claim to depend from and/or incorporate any feature of any other claim although not originally claimed in that manner.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the invention will now be described by way of example only with reference to the accompanying drawings in which:

FIG. 1 shows an offshore structure fixed to foundation piles;

FIG. 2 shows the interface between a leg of an offshore structure and a foundation pile;

FIG. 3 is a side-view showing a stab-in portion of a leg of an offshore structure;

FIG. 4 is a schematic cross-section showing a leg of an offshore structure inserted into a foundation pile;

FIG. 5 is the arrangement of FIG. 4 including an apparatus for applying grout;

FIG. 6 a is a schematic showing the apparatus of FIG. 5 in a first position;

FIG. 6 b is a schematic showing the apparatus of FIG. 5 in a second position;

FIG. 7 shows a rigid tube of the apparatus of FIGS. 5, 6 a and 6 b;

FIG. 8 shows a funnel guide for guiding the apparatus of FIGS. 5 to 7 , in use; and

DETAILED DESCRIPTION

Certain terminology is used in the following description for convenience only and is not limiting. The words ‘right’, ‘left’, ‘lower’, ‘upper’, ‘front’, ‘rear’, ‘upward’, ‘down’ and ‘downward’ designate directions in the drawings to which reference is made and are with respect to the described component when assembled and mounted. The words ‘inner’, ‘inwardly’ and ‘outer’, ‘outwardly’ refer to directions toward and away from, respectively, a designated centreline or a geometric centre of an element being described (e.g. central axis), the particular meaning being readily apparent from the context of the description. In particular, the words “upstream” and “downstream” designate directions which refer to the direction of fluid flow within the pipe.

Further, as used herein, the terms ‘connected’, ‘attached’, ‘coupled’, ‘mounted’ are intended to include direct connections between two members without any other members interposed therebetween, as well as, indirect connections between members in which one or more other members are interposed therebetween. The terminology includes the words specifically mentioned above, derivatives thereof, and words of similar import.

Further, unless otherwise specified, the use of ordinal adjectives, such as, “first”, “second”, “third” etc. merely indicate that different instances of like objects are being referred to and are not intended to imply that the objects so described must be in a given sequence, either temporally, spatially, in ranking or in any other manner.

Referring now to FIG. 1 , there is shown an offshore structure 1 for supporting a payload (not shown) above the surface of a body of water. In different examples, the payload (not shown) may be a wind turbine or an oil and gas platform. The offshore structure 1 includes a jacket 2 having three legs 3. In this example, the legs 3 are interconnected by cross-members 4. Each leg 3 has a main body 3 a and stab-in portion 3 b (shown more clearly in FIG. 3 , in particular). Each of the main body 3 a and stab-in portion 3 b are hollow steel tubes in this example. In other examples, the main body 3 a and stab-in portion 3 b of each leg 3 may comprise a different material and construction. In this example the offshore structure 1 has three legs 3, but it will be appreciated that the offshore structure 1 may have any number of legs 3, including four legs 3.

The offshore structure 1 is secured to the seabed by fixing it to the foundation piles 5, which are hollow steel tubes pre-piled into the seabed in this example. The stab-in portion 3 b of each leg 3 is received within an open end 50 of a respective foundation pile 5. A cementitious material, in the form of grout, is used to at least substantially fill the remaining region or volume between the stab-in portion 3 b and foundation pile 5 (made up of regions A and B, as shown in FIGS. 4 and 5 , in particular), and thereby fix the jacket 2 to the foundation pile 5.

Referring now to FIG. 2 there is shown the interface between a jacket 2 and a foundation pile 5 with the stab-in portion 3 b inserted into the foundation pile 5. Located between the main body 3 a and stab-in portion 3 b on each leg 3 is a flange 30 a. The flange 30 a is radially extending. When a respective stab-in portion 3 b is located within a respective foundation pile 5, the flange 30 a braces against the rim at the open end 50 of the foundation pile 5. The position of the flange 30 a on the leg 3 defines the amount of the leg 3, in particular the stab-in portion 3 b, that is inserted into the foundation pile 5. Extending through the flange 30 a is an overflow outlet 35 b (shown more clearly in FIG. 4 ), allowing the overflow of excess grout during a grouting operation as described further hereinafter.

Referring now to FIG. 3 , there is shown a stab-in portion 3 b of a leg 3. At an end of the stab-in portion 3 b, distal of the flange 30 a, is a tapered end portion 30 b. The end portion 30 b may be integral to the tubular part of the stab-in portion 3 b, or it may be formed by a cap that is inserted into an end of the stab-in portion 3 b. The end portion 30 b includes a plurality of circumferentially spaced, radially extending fins 31 b. The geometry of the end portion 30 b is configured to ease the location of the stab-in portion 3 b within a respective foundation pile 5 and therefore make it easier to insert the leg 3 into the foundation pile 5.

Extending between the flange 30 a and end portion 30 b is a sidewall 32 b. In the present example the stab-in portion 3 b includes a plurality of shear keys 33 b located along the length of the sidewall 32 b, between the flange 30 a and end portion 30 b. The shear keys 33 b are preferably formed by ridges in the surface of the stab-in portion 3 b. The shear keys 33 b are configured to provide resistance to relative translational movement between the stab-in portion 3 b and the foundation pile 5 after the leg 3 has been grouted to the foundation pile 5, to provide a better fixing of the leg 3 to the foundation pile 5.

Referring now to FIG. 4 , as described above when the stab-in portion 3 b is located within a foundation pile 5, the flange 30 a acts as a stopper, limiting the depth to which the stab-in portion 3 b extends into the open end of the foundation pile 5.

In some examples, an underside of the flange 30 a has a circumferentially extending seal 34 b, in the form of an elastomeric O-ring configured to seal against the free-end 50 of foundation pile 5. Radially inward of the circumferentially extending seal 34 b is the overflow outlet 35 b, described above. The flange 30 a may also include a further aperture, in form of inlet 31 a for receipt of the stinger 7, or rigid tube 71 thereof (as shown in FIG. 5 ).

FIG. 4 shows dredge line D. The dredge line D is the level of the sea floor within the foundation pile 5 after a piling operation has been carried out. In the present example, the dredge line D lies below the surrounding sea floor (not shown), but may alternatively be level with, or above the sea floor. As illustrated, the leg 3 is inserted into the foundation pile 5 such that the end portion 30 b is spaced from the sea floor within the foundation pile 5 (i.e. spaced from the dredge line D).

With the stab-in 3 b located within the foundation pile 5, a region A is described between the end portion 30 b and the dredge line D within the foundation pile 5. Additionally, an annular region B is described between the sidewall 32 b and internal wall 51 of the foundation pile 5. During a grouting process (described below) grout is provided to region A and region B. When region A and region B are full grout will overflow the annular region B through outlet 35 b. The seal 34 b is configured to prevent the leakage of grout from points or areas other than the outlet 35 b.

It will be appreciated that, in the present example, in the case of a jacket 2 having a plurality of legs 3, each will have an arrangement as per FIG. 4 . Here, the jacket leg(s) 3 and stab in portion(s) 3 b do not comprise internal piping or hoses for conveying grout material to the regions.

To secure the leg 3 to the foundation pile 5 the sea floor is preferably dredged prior to installing foundation piles 5. Then, one or more foundation piles 5 are piled into the sea floor to a desired depth and such that an open end 50 of each pile 5 protrudes from the sea floor. The jacket 2 is then lowered towards the sea floor and respective stab-in portions 3 b are located within open ends 50 of respective foundation piles 5. The jacket 2 is lowered until each flange 30 a braces against a respective open end 50, describing regions A and B. Grout is then applied to the regions A and B, as described below.

Referring now to FIGS. 5 to 7 , there is shown an apparatus for applying grout to an offshore structure 1 having a leg 3 inserted into a foundation pile 5. In particular, the apparatus is for filling the regions A and B as described above with grout. In the present example, a stinger 7 extends from a vessel V (FIGS. 6 a, 6 b ) on the surface. The stinger 7 extends into the volume described between the stab-in portion 3 b and the foundation pile 5 through the inlet 31 a.

As shown most clearly in FIGS. 6 a and 6 b , the stinger 7 has a flexible conduit or hose 70 having a first end 70 a connected to a source of grout, in particular a pump unit P onboard the vessel V, and a second end 70 b connected to a rigid tube 71. The rigid tube 71 is formed of steel in this example. The flexible conduit 70 is hoisted by a crane C onboard the vessel V but may additionally or alternatively be located on a reel or spool. The flexible conduit 70 may support the weight of the rigid tube 71 as well as being a conduit for grout, or alternatively the rigid tube 71 is suspended on a tether and a separate conduit is provided to supply grout to the rigid tube 71. For example, the rigid tube 71 may be suspended on a chain, while a hose supplies grout to the rigid tube 71.

As shown in FIG. 7 , in particular, the rigid tube 71 has a first, open end 710 for connection with the flexible conduit 70, and a second, closed end 711 opposite the first end 710. The sidewall 712 of the rigid tube 71, proximate the closed end 711 in this example, has an outlet 72 for grout. The closed end 711 is preferably provided by a welded cap but may be folded closed or plugged.

Indicia or markings 73 are provided along the length of the rigid tube 71, on an external surface of the sidewall 712. In the present example, the indicia or markings 73 specify the distance from the centre of the outlet 72 to discrete points along the length of the rigid tube 71. Such indicia 73 provide an indication of the depth to which the outlet 72 is inserted into the volume between the stab-in portion 3 b and foundation pile 5.

Alternatively, the indicia 73 may specify the distance from closed end 711 to discrete points along the length of the rigid tube 71.

A grouting operation using the apparatus of FIGS. 5 to 7 is carried out as shown in FIGS. 5, 6 a and 6 b, in particular. The stinger 7 is connected to the pump unit P and lowered from the vessel V toward the seabed S (FIGS. 6 a and 6 b ). The rigid tube 71 is located with the inlet 131 a and lowered into the volume described between the stab-in portion 3 b and foundation pile 5.

In a first stage, the stinger 7 is lowered to a first position P1 as shown by the broken outline in FIG. 6 and also shown in FIG. 6 a . In the first position P1, the closed end 711 is located at or approximate the dredge line D within the foundation pile 5. To reach this position the stinger 7 may be lowered until the tension in the tether is decreased, indicating that the stinger 7 is resting on the sea floor. The stinger 7 may then optionally be raised slightly to lift it off of the sea floor. Grout is then conveyed, using the pump unit P, along the stinger 7 to the outlet 72. Grout is conveyed until the region A is filled. Preferably, a predetermined volume of grout is conveyed into region A. The predetermined volume is based on the known internal diameter of the foundation pile and the specified distance between the sea floor within the foundation pile 5 (i.e. the dredge line) and the stab-in portion 3 b. In other examples, the stinger 7 and/or stab-in portion 3 b may include a sensor that detects when the grout in region A reaches a certain level along the length of the rigid tube 71 corresponding to the desired depth of region A.

In the present example, once region A is full, the stinger 7 is then raised by the crane C and the grout filling region A is left to cure to a predetermined degree. The degree of curing may be determined based on the water temperature and a known curing rate of the grout. The grout applied to region A may be left to cure until firm or hard, or substantially firm or hard. The grout applied to region A may be left to cure until it reaches its final set.

The stinger 7 may be raised to a second position P2, as shown by the solid outline in FIG. 5 and also shown in FIG. 6 b . The second position P2 is above the first position and above the region A. In some examples, the stinger 7 is removed from the foundation pile 5 and moved to other foundation piles 5 of the offshore structure 1 to repeat application of grout to region A, as described further hereinafter.

After the grout filled region A has cured to the predetermined degree the stinger 7 is moved to the second position P2.

Then, with the stinger 7 in the second position P2, grout is conveyed, using the pump unit P, along the stinger 7 to the outlet 72 to fill region B. Grout is conveyed until region B is filled.

In the present example, the filling of region B is identified by the presence of grout at overflow outlet 35 b. However, it will be appreciated that instead of providing an overflow outlet 35 b, the filling of region B may be determined using a density meter or density gauge, or acoustically, for example by an acoustic sensor on a remotely operated vehicle (ROV), or on the leg 3. Alternatively, filling of region B may be determined by using a pressure sensor or transducer located either on the stinger 7 or within the volume described by regions A and B. In such a case, in the absence of overflow outlet 35 b (or with a restricted overflow outlet 35 b), once region B is full a pressure increase may be detected if the pump unit P remains activated. In other examples, a predetermined volume of grout is conveyed into the region B based on the known dimensions of the stab-in portion 3 b and the foundation pile 5. Such an example might be advantageous where no flange 30 a is provided, to prevent overflow of the grout.

Referring now to FIG. 8 , there is shown a funnel guide 8 for guiding a stinger 7 through the inlet 31 a in the flange 30 a and into the volume between the stab-in portion 3 b and foundation pile 5. The funnel guide 8 has a conical portion 80 that tapers towards the inlet 31 a. In the present example, in connection with the conical portion 80 is a sleeve 81, configured to be inserted into the inlet 31 a.

In examples, the funnel guide 8 may be formed integrally with the flange 30 a.

In use, the funnel guide 8 is used to provide a larger target area for the stinger 7, in particular the rigid tube 71 thereof. This helps locate the stinger 7 with the inlet 31 a when it is lowered towards the seafloor.

It will be appreciated by those skilled in the art that several variations to the aforementioned embodiments are envisaged without departing from the scope of the invention.

It will also be appreciated by those skilled in the art that any number of combinations of the aforementioned features and/or those shown in the appended drawings provide clear advantages over the prior art and are therefore within the scope of the invention described herein. 

1. An apparatus for applying grout in a region between a tubular sub-sea foundation pile and a leg of an offshore structure inserted into the foundation pile, the apparatus comprising a rigid tube adapted to be inserted into the region, the rigid tube comprising an inlet for receiving grout, and an outlet.
 2. The apparatus according to claim 1, wherein the leg of the offshore structure does not comprise any internal and/or integrated means for conveying grout into the tubular sub-sea foundation pile.
 3. The apparatus according to claim 1, wherein the rigid tube comprises a sidewall, and wherein the outlet is disposed in the sidewall.
 4. The apparatus according to claim 1, comprising a closed end opposite to the inlet end.
 5. The apparatus according to claim 1, wherein the rigid tube comprises a plurality of outlets disposed in the sidewall, the outlets being circumferentially spaced thereabout.
 6. The apparatus according to claim 1, wherein the sidewall of the rigid tube comprises indicia, the indicia configured to provide, in use, an indication of the depth to which the outlet is inserted into a foundation pile.
 7. The apparatus according claim 4, wherein the closed end is provided by a plug or cap.
 8. The apparatus according to claim 1, further comprising a flexible conduit, the flexible conduit having a first end for connection with a source of grout, and a second end connected to the rigid tube.
 9. The apparatus according to claim 1, wherein the rigid tube has a diameter of between 2 and 4 inches.
 10. The apparatus according to claim 8, wherein the flexible conduit has a diameter of between 2 and 4 inches.
 11. The apparatus according to claim 1, further comprising a flange configured to be attached to the leg and limit the extent to which the leg can be inserted into the foundation pile.
 12. The apparatus according to claim 11, wherein the flange comprises a funnel guide arranged to guide the rigid tube into the foundation pile.
 13. The apparatus according to claim 12, wherein the flange further comprises one or more apertures extending therethrough for locating the rigid tube, in use, relative to a foundation pile, the or each aperture having a conical portion extending thereabout to guide the rigid tube towards the aperture.
 14. An offshore structure foundation building system, comprising an apparatus as claimed in claim 1, an offshore structure having a leg, and a foundation pile.
 15. The offshore structure foundation building system according to claim 14, wherein the leg of the offshore structure does not comprise any internal and/or integrated means for conveying grout into the tubular sub-sea foundation pile.
 16. A kit of parts comprising a rigid tube according to claim 1 and a flexible conduit having a first end for connection with a source of grout, and a second end connected to the rigid tube.
 17. A method of fixing an offshore structure to a pre-piled sub-sea foundation pile, wherein the foundation pile comprises a tube piled into the sea floor and the offshore structure comprises a leg inserted into the foundation pile, wherein the method comprises lowering a rigid tube into a region described between the foundation pile and the leg such than an outlet of the rigid tube is at a first position, and applying grout to a first region between an end of the leg and the sea floor within the foundation pile via the rigid tube.
 18. The method according to claim 17, wherein the leg does not comprise any internal and/or integrated means for conveying grout into the tubular sub-sea foundation pile. 